Electrical Maintenance Engineer Interview Questions UK: 8 Real Questions and What Interviewers Want

Most Electrical Maintenance Engineer interviews in the UK follow a pattern, and knowing it beats guessing. Below are eight questions from our bank of 16, each with a note on what the interviewer is really after.

Eight Electrical Maintenance Engineer interview questions, and what the interviewer is thinking

1. How do you test the health of a three-phase motor, and what do insulation resistance and polarisation index tell you?

Why they ask: Motor testing is routine for an electrical maintenance engineer, and they want to see correct, safe method.

2. How do you use thermal imaging in electrical maintenance, and what would you do if you found a hot spot?

Why they ask: Thermography is a common predictive tool, and they want to know how you interpret and act on findings.

3. A variable speed drive trips on a fault code. How do you diagnose and resolve it?

Why they ask: VSDs are everywhere in industry, so they expect a methodical approach.

4. What are the observation codes C1, C2, C3 and FI on an EICR, and how do you decide which to apply?

Why they ask: Periodic inspection reports are routine, and the coding shows whether you understand risk.

5. What additional requirements apply to maintaining electrical equipment in a hazardous area under DSEAR and ATEX?

Why they ask: Many sites have explosive atmospheres, and wrong work on Ex equipment can be catastrophic.

6. A motor keeps tripping on thermal overload every few hours. The operators say it is a nuisance and want the overload setting increased. What do you do?

Why they ask: They want to see that you find the cause instead of defeating the protection.

7. Tell me about a time you planned and carried out electrical maintenance during a planned shutdown.

Why they ask: Shutdown work shows planning, coordination and safety skills.

8. What does a typical day for an electrical maintenance engineer look like, and what attracts you to the role?

Why they ask: They want to confirm you understand the pace and responsibilities of maintenance work.

A sample answer to question 1

How do you test the health of a three-phase motor, and what do insulation resistance and polarisation index tell you?

First I isolate, prove dead and lock off, and discharge any capacitors or the motor windings after testing. I disconnect the motor from the starter or drive, because applying a megger test voltage through a VSD can destroy it. Using an insulation resistance tester, typically at 500 or 1000 volts depending on the motor's rating, I test each winding to earth, then between windings. As a rule of thumb the reading should be well above 1 megohm, and healthy windings often give hundreds of megohms, but I compare with previous results, as a falling trend matters more than a single reading. The polarisation index is the ten-minute reading divided by the one-minute reading. A value of 2 or more suggests dry, healthy insulation, while a value near 1 suggests moisture or contamination. If insulation is low because of damp, I might dry the motor out in a controlled way, but if it is degraded, I plan a rewind or replacement.

Common mistake to avoid: Megger testing through a drive; relying on a single reading

Want the rest?

Full model answers, key points and common mistakes for all 16 questions are on the Electrical Maintenance Engineer interview questions page. The first five are free, no sign-up needed.